Elemental sulphur is a by-product of oil and gas refining processes. A known application of the elemental sulphur obtained as a by-product of oil and gas refining is its use as a binder in sulphur cement or in other sulphur cement products, for example sulphur cement-aggregate composites like sulphur mortar, sulphur concrete or sulphur-extended asphalt.
In refineries, sulphur compounds in liquid hydrocarbonaceous streams are typically converted by reaction with hydrogen into hydrogen sulphide. Thus, a gaseous stream comprising hydrogen sulphide and hydrogen is obtained. The hydrogen sulphide separated from this hydrogen sulphide and hydrogen mixture or the hydrogen sulphide separated from natural gas is typically converted into elemental sulphur. A well-known example of such process is the so-called Claus process.
Conversion of hydrogen sulphide into elemental sulphur using the Claus process has certain disadvantages. The oxidation step in the Claus process is not selective for hydrogen sulphide, therefore separation of the hydrogen sulphide from the remainder of the gas stream is necessary. In view of thermodynamic limitations, no complete conversion of hydrogen sulphide in a single process stage can be obtained.
An alternative process for the conversion of hydrogen sulphide into elemental sulphur is the selective oxidation of hydrogen sulphide in hydrocarbonaceous gas streams. Such selective oxidation processes are disclosed in for example U.S. Pat. Nos. 4,886,649, 4,311,683 and 6,207,127. Compared to the Claus process, selective oxidation has several advantages. An advantage is that a high conversion of hydrogen sulphide can be obtained in a single process stage. Another advantage is that the oxidation is selective for hydrogen sulphide, thus avoiding the need for separation of the hydrogen sulphide from the other gas components. A disadvantage is, however, that catalyst deactivation due to clogging of the catalyst with the sulphur formed may occur. In order to avoid clogging, the prior art selective oxidation processes typically use a low concentration of hydrogen sulphide in the feed gas, typically at most 1 wt %.